Anastomose porto-cava experimental: estudo clínico, anatomoangiográfico e anatomopatológico em ratos

Abstract

In order to study the evolution of clinical, hepatic morphological and angiographic alterations of the portal venous system of normal rats submitted to portocaval anastomosis, for a period of up to six months, 135 male animals were used, with an average weight of 242 grams, distributed in two experimental groups, characterized as follows: control group (41 rats submitted to simulated operation) and portocaval anastomosis group (72 rats submitted to portocaval anastomosis terminolateral). The rest of the animals were used for the standardization of the splenoportography technique and anatomical studies. In the clinical evaluation, the following attributes were considered: body weight, food intake, 100 g of body weight, fluid intake, 100 g of body weight and diuresis, 100 g of body weight. The angiographic study was performed by means of serial postmortem splenoportography, using 75% Hypaque and Schlesinger mass as contrast substances. The anatomopathological examination was performed through light microscopy, comparing it with the radiological findings, and also determining the liver weight/body weight ratio. Mortality rates were 17% and 55.5%, respectively, for the control and portocaval anastomosis groups. The diversion of portal blood to the systemic circulation caused important clinical effects in the rat, over the six months of the experiment, characterized by loss of body weight and decrease in food intake in the first month after surgery, increased fluid intake and diuresis, in addition to the occurrence of urinary lithiasis and testicular atrophy. The postoperative complications that caused deaths in animals with Eck's fistula were occlusive thrombosis at the level of the portocaval anastomosis, lithiasic urethral obstruction and pulmonary infection. Serial postmortem splenoportography allowed detailed anatomoradiological studies of the rat's portal venous system. Better results were obtained when 75% Hypaque was used as contrast material than Schlesinger's mass. Of the 26 splenoportography analyzed in rats with Eck's fistula, in 15 (57.6%) the portocaval anastomosis was patent, without stenosis and no evidence of any type of collateral irculation. Variable degree stenosis of the venous anastomosis was observed in 7 angiographies (26.9%), and in another 4 (15.3%), occlusion was demonstrated. The development of collateral vessels was observed in 6 splenoportography (23%), in which the venous anastomosis was stenosed or occluded. Regarding the type of collateral circulation, portosystemic collateral vessels were detected in six angiograms, and in only one examination the formation of portohepatic collateral vessels was verified. Eck's fistula caused important anatomopathological effects in the rat liver, characterized by a decrease in the liver weight/body weight ratio, atrophy of centrilobular hepatocytes and an increase in the volume of liver cells in periportal locations. These changes were more evident in the 3rd month after surgery, with a tendency to regression in the 6th month postoperatively.